Is it possible to insert my church logo on the bottom corner of a slide, just as you might insert a text box in the corner to show the church name, Bible version, etc?
Yes! You can add a Foreground image to your slide. Then you can right click on it and check show on all slides, that way it shows on each slide in your service item. the button is right next to the textbox button on the toolbar
and we are actually working on a new feature which will save your selected ‘church logo’ for quick access just like the church name field.
Does this apply to song slides as well? Can I put a symbol on only one slide in a song?
Yes you can Gene. Simply right-click on the image, and select either "Show on All Slides" to enable/disable.